AdGuard Home DNS — Ad Blocking and Caching for Home Lab Enthusiasts (Part 1)

Introduction

You’ve probably already got a few things running in your home lab — maybe a NAS, a Docker stack, or a Pi-hole instance quietly managing DNS traffic. But there’s a point every home labber reaches: you start wondering if you can push your network just a little further. Fewer ads. Faster page loads. More control over what actually leaves your network.

That’s usually when you stumble across AdGuard Home.

On the surface, AdGuard Home looks like another ad blocker. But it’s not your typical browser extension — it’s a DNS-based network filter that works at the root of your home network. Instead of blocking ads after they’ve already loaded in your browser, AdGuard Home stops those requests before they even reach your devices. The result? No ads on your smart TV, phone, tablet, or even your fridge that somehow talks to ad servers.

But what really makes AdGuard Home interesting for home lab enthusiasts isn’t just the ad blocking — it’s the DNS caching. Once you’ve got it running, AdGuard Home doesn’t just filter requests; it remembers them. Every time you visit a site, that DNS lookup gets stored locally, meaning the next time your device asks for the same address, AdGuard can respond instantly — no external query needed. The result is a leaner, faster, more self-reliant home network.

In this guide, you’ll learn:

What AdGuard Home actually does (and how it compares to Pi-hole).
How DNS filtering and caching work under the hood.
And how to tune it for the best mix of privacy, speed, and reliability.

Whether you’re looking to replace your Pi-hole setup or just expand your lab’s capabilities, this article will walk you through how AdGuard Home can take your network from “working” to optimised.

What Is AdGuard Home?

At its core, AdGuard Home is a network-wide ad blocker and DNS server.
If you’ve used browser-based ad blockers before, you already know what blocking ads looks like — but AdGuard Home works at a completely different layer of your network. Instead of filtering ads inside your browser, it stops ad-related requests before they ever leave your network.

🧠 A Quick Refresher: What DNS Actually Does

Think of DNS (Domain Name System) as the phonebook of the internet.
Every time you visit a website like youtube.com, your device asks, “What’s the IP address for this domain?” That question — called a DNS query — gets sent to a DNS server somewhere on the internet, which responds with the answer.

So, for example:

youtube.com → 142.250.190.206

That process happens constantly. Every app, every device, every time you open something online — dozens or hundreds of DNS lookups occur in the background.

Now, what AdGuard Home does is intercept those DNS queries locally. Instead of your devices sending them to your ISP or Google’s DNS, they send them to AdGuard Home, which runs inside your own network — on your Raspberry Pi, NAS, Docker container, or even a virtual machine.

🧩 What Makes It Different from Standard DNS

A normal DNS server just answers the question — it finds the IP and sends it back.
AdGuard Home adds a layer of logic on top: it checks each domain request against a list of known ad servers, trackers, and malicious hosts.

If the domain matches one on the blocklist (for example, ads.facebook.com), AdGuard Home simply refuses to return a valid IP address.
Your browser or app never connects to that domain — meaning the ad or tracker request just disappears quietly in the background.

The result:

No banner ads on web pages.
No YouTube app ads on your smart TV.
No analytics pings from random IoT devices.

And because AdGuard Home operates at the DNS level, this applies to every device connected to your home network — even ones that can’t run traditional ad blockers.

⚙️ It’s Also Your Local DNS Cache

In addition to blocking, AdGuard Home keeps a local cache of DNS results. That means when you visit a site again, it doesn’t have to ask an external server all over again — it just replies from memory.

This is what makes pages load faster, and it also reduces the number of external DNS lookups leaving your network. It’s faster, quieter, and a little more private.

In short, AdGuard Home isn’t just an ad blocker.
It’s your home DNS resolver, filter, and cache, all rolled into one tidy piece of software.

How AdGuard Home Blocks Ads (DNS Filtering Explained)

You already know that DNS is like your internet’s phonebook.
Every time a device on your network wants to visit a site or load an ad, it asks your DNS server for the IP address that matches the domain.

What AdGuard Home does is act as a smart DNS gatekeeper — one that knows which domains are “good” and which ones are better left unanswered.

🧱 Step 1: The DNS Query Flow

Let’s look at a simple example: you open a webpage with ads — say a news site.

Behind the scenes, your browser makes multiple DNS requests:

newswebsite.com
cdn.newswebsite.com
ads.thirdpartyadserver.com
analytics.tracker.net

Normally, your DNS resolver would look up all of these and return IPs for each.
But AdGuard Home checks every one of those domains against its filter lists before responding.

🕵️ Step 2: The Filter Lists

Filter lists are the heart of AdGuard Home’s blocking power.
They’re plain text files containing thousands of known ad, tracker, and malware domains. You can think of them as DNS-level blacklists.

When a request like ads.thirdpartyadserver.com comes in, AdGuard Home checks:

Is this domain on my blocklist?

If the answer is yes, it won’t forward the request to any upstream DNS server. Instead, it simply replies with a null response — usually an empty IP or 0.0.0.0.

From your browser’s perspective, that ad domain just doesn’t exist.
No connection is made, no ad data is downloaded, and no trackers run scripts in the background.

⚙️ Step 3: Upstream DNS (for Clean Requests)

For domains that aren’t on the blocklist, AdGuard Home forwards the query upstream — to whatever DNS servers you’ve configured.
This could be:

Cloudflare DNS (1.1.1.1)
Google DNS (8.8.8.8)
Quad9, NextDNS, or even your own recursive resolver like Unbound

Once it receives the valid IP address, AdGuard Home passes it back to your device — and stores the result in its local cache.

So the next time any device on your network requests that same domain, AdGuard Home can answer instantly, without contacting the upstream resolver again.

🧩 Step 4: Whitelists and Custom Rules

Of course, not every domain on a blocklist should be blocked.
Some websites load essential assets from third-party domains that occasionally get caught in broad filters. That’s where whitelists and custom rules come in.

AdGuard Home lets you manually:

Whitelist domains you trust (e.g. cdn.safewebsite.com)
Blacklist additional domains you want blocked
Create custom filtering rules using wildcards or specific DNS patterns

This gives you granular control — perfect for home labbers who enjoy fine-tuning their environment.

🔍 Step 5: Monitoring in Real Time

One of the most satisfying parts of running AdGuard Home is watching it work in real time.
Its web dashboard shows:

Total DNS queries processed
How many were blocked
Which devices are the most active
Which domains are being blocked the most

You’ll be surprised at how much background traffic your devices generate — smart TVs, phones, even IoT devices constantly talking to ad and telemetry servers. AdGuard Home gives you visibility and control over all of it.

🧠 The Big Picture

Here’s the beauty of DNS-level filtering:

It works network-wide — across every device, app, and platform.
It stops requests before they leave your network, improving privacy.
And it reduces data usage and page load times, since ad and tracker content never gets downloaded.

In short, AdGuard Home doesn’t just hide ads — it prevents them from existing in your network in the first place.

How DNS Caching Works in AdGuard Home

Every time a device asks for a website, it starts with a DNS query —
“Hey, what’s the IP address for this domain?”

If that domain hasn’t been looked up recently, your DNS resolver (in this case, AdGuard Home) has to ask an upstream server for the answer. That process, while quick, still adds a bit of delay and external dependency.

DNS caching solves this problem by remembering answers for a certain amount of time, so your devices don’t need to repeat the same question again and again.

⚡ The Core Idea: Don’t Ask Twice

When AdGuard Home receives a DNS response from an upstream server, it saves it locally — this is your cache.

For example:

example.com → 93.184.216.34  (cached for 3600 seconds)

The “3600 seconds” bit comes from the TTL (Time To Live) — a value that tells your DNS server how long it can keep that answer before it should check again.

So if you visit example.com again within that hour, AdGuard Home doesn’t bother the upstream DNS resolver. It simply replies instantly from its local memory.

The result:

Faster lookups (no waiting for external responses)
Less upstream traffic (fewer external DNS queries)
Lower latency across your entire home network

🧠 What’s Actually Happening Under the Hood

AdGuard Home keeps a local cache database in memory.
When a DNS query comes in, it checks:

Is the domain in my cache?
Is the cached record still valid (not expired)?

If both are true, AdGuard Home serves that cached record immediately — usually in less than a millisecond.

If not, it forwards the request to an upstream DNS server, waits for the answer, sends it back to your device, and stores it in the cache for future use.

This process is completely automatic. You don’t have to do anything to enable it — AdGuard Home handles caching by default.

🧩 How It Helps in a Home Lab Environment

In a typical home lab, you might have:

Several Docker containers pulling updates
Smart devices pinging cloud APIs
Web interfaces loading dashboards or external scripts

Without caching, each of these services repeatedly queries the same domains — often hundreds of times a day. That means unnecessary network chatter and slower responses.

With AdGuard Home caching those DNS lookups:

Common domains (like docker.io, ubuntu.com, github.com) resolve instantly
Repeated queries from different containers or devices get answered locally
Your network stays snappier and more efficient

It’s a small performance boost, but one that adds up fast across multiple machines.

⚙️ Adjusting Cache Settings (Optional)

By default, AdGuard Home respects the TTL values set by the upstream DNS servers.
However, you can tweak caching behavior the settings if you want more control.

Under Settings → DNS Settings → Cache Configuration, you can:

Increase or decrease the maximum cache size
Adjust how long records are stored
Clear the cache manually if needed

This is useful if you’re experimenting with your own DNS resolver setup — for example, pairing AdGuard Home with Unbound for full local recursion and privacy.

🧩 Cached vs Non-Cached Query Flow

To visualise it:

Every cached hit removes an entire round trip to the upstream DNS — saving milliseconds per request, and significantly reducing external lookups over time.

🧮 Fun Fact: Measuring Cache Efficiency

In the AdGuard Home dashboard, you can actually track cache efficiency.
The “Statistics” panel shows how many queries were:

Blocked (ads, trackers)
Cached (answered locally)
Forwarded (sent upstream)

If you see your “Cached” percentage climbing above 50–60%, it means your setup is performing very efficiently — your DNS resolver is learning and adapting to your usage patterns.

✅ Why It Matters

DNS caching might sound like a small detail, but it’s a core performance feature.
It makes your network:

Faster – instant responses for repeated domains
More private – fewer outbound requests to public resolvers
More reliable – your devices can resolve frequent domains even if your internet connection hiccups briefly

It’s one of those behind-the-scenes optimization that, once it’s running, you don’t notice — because everything just works faster.

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AdGuard Home DNS for Newbies - Part 1